Seres reports SER-155 irEC trial data as it seeks partners and cuts facility costs
Seres said 80% of patients in an MSK-run trial of SER-155 hit the day-15 response endpoint, while the company works to fund its allo-HCT and IBD programs.
Seres Therapeutics reported second quarter 2026 financial results and business updates on August 5, 2026, highlighting topline data from an investigator-sponsored trial of its live biotherapeutic SER-155 in immune checkpoint inhibitor-related enterocolitis (irEC), conducted by Memorial Sloan Kettering Cancer Center.
In the open-label study, registered as NCT06801067, 15 participants with moderate-to-severe (Grade 2-3) irEC who were naïve to immunosuppressive therapy were evaluated.1 Twelve of 15 participants, or 80%, achieved an immunosuppressive-free clinical response at day 15, the primary efficacy endpoint, defined as at least a 1-grade improvement in diarrhea symptoms without immunosuppressive therapy.1 SER-155 was generally well tolerated with no safety concerns identified and no serious adverse events assessed as related to SER-155.1 Seres said the results support continued development of SER-155 in irEC and that it is engaging potential partners, including companies with ICI franchises, as it evaluates next steps.1
On the company's other programs, SER-155 remains Phase 2 ready for prevention of bloodstream infections in patients undergoing allogeneic hematopoietic stem cell transplant for blood cancer, and has received Breakthrough Therapy and Fast Track designations for that indication.1 Seres continues IND-enabling work on SER-603 for inflammatory bowel disease and is seeking collaborators for its clinical advancement.1 The company is also progressing SER-428, an oral liquid formulation based on SER-155 strains supported by a CARB-X grant, and is designing a Phase 1b open-label trial with Columbia University to test it in medical ICU patients at high infection risk.1
On finances, Seres agreed on July 31 to terminate its lease at 200 Sidney Street in Cambridge, eliminating remaining obligations as of December 31, 2026 in exchange for certain consideration and reducing facility cash costs starting in 2027.1 As of June 30, 2026, Seres had $15.6 million in cash and cash equivalents.1 Including expected Nestlé milestone payments, the company said it expects to fund operations through the first quarter of 2027, a projection that excludes proceeds from any future partnerships or other capital sources.1
Written by readthrough’s AI from the linked primary sources and fact-checked against them automatically before publishing. Not investment advice.